Earth drilling devices, in particular horizontal drilling devices, are used to introduce earth drill holes into the soil by trenchless construction for supply and waste lines, for example, or to replace already installed old lines without a trench. To introduce the earth drill hole, generally a drill string having drill string sections is used, wherein the drill string sections are connectable to each other.
The use of a slide that can be moved back and forth in a frame for advancing and/or retracting a drill string is known from EP 0 886 034 B1, for example. The slide has a seat for a drill string section such that the drill string section can be moved in the seat in the direction of a feed axis to create the earth drill hole. The drive acting on the drill string section can act on the drill string section in the seat in a rotational and/or translatory manner.
For driving the slide in the frame in a translatory manner, it is known to use a plurality of hydraulic motors for large and powerful earth drilling devices, said motors being used to drive the slide in the frame, i.e., for the back and forth movement. Each of the hydraulic motors can have a planetary gear which has a feed pinion that engages with a rack securely arranged in the frame and moves the slide in the frame, in particular in a translatory manner. For large and powerful earth drilling devices, it is therefore known to use more than one motor in order for example to be able to perform earth drilling in solid ground. The use of several motors means providing hydraulic connecting lines for each of the motors and providing a rack fastened to the frame for each of the motors. In addition, significant mechanical and hydraulic losses can result. Furthermore, the construction is relatively large.